1. Technical Field
The invention relates to pest control. More particularly, the invention relates to a method and apparatus for the use of pressurized exhaust gases to control rodents.
2. Description of the Prior Art
The infestation of cultivated lands by underground rodents has plagued farmers, gardeners, and groundskeepers alike for generations. Modern agricultural practices, such as weed-free border areas, as well as the wide spread use of sprinkler irrigation, have actually increased the amount of acreage which is a preferred habitat for gophers, moles, and ground squirrels. Perennial farmed crops, such as hay, and orchards are particularly difficult to protect. Thus, farmers pay a heavy price each year in lost productivity, in addition to the cost of ineffective control measures. For example, Kansas State University estimates that pocket gophers alone are responsible for a 20 to 50 percent drop in productivity in infested alfalfa fields and grassland.
Current control measures used by agriculturists include trapping, flooding, and poison bait inserted in the natural burrow or in an artificial burrow created with a chisel tooth. Existing devices using non-pressurized exhaust gases, such as carbon monoxide, from an internal combustion engine to poison underground rodents are labor intensive and ineffective. They require operators to dig out each individual burrow entrance and they result in very low kill rates. Poisoned bait, either placed in existing burrows by hand or in artificial burrows created for this purpose, has been partially effective in the past with good management, but current regulations limiting the kind and concentration of poison in rodent baits have seriously compromised its effectiveness. In addition, the creation of an artificial burrow to apply such bait destroys a portion of the very crop it is designed to protect.
The damage done by burrowing rodents is two-fold. Both the burrows and the rodents themselves damage the root system of crops and landscaping, resulting in reduced yields. In addition, gophers and ground squirrels create mounds of dirt excavated from their tunnels. These mounds, up to two feet in diameter and eight inches high, are a serious problem for hay farmers because they can break farming machinery and contaminate the hay with dirt. For example, mechanical harvesters for fruit orchards require flat, level ground between tree rows, so as not to damage the trees. Land that is riddled with gopher mounds thus requires the farmer to perform continual land shaping for harvest operations.